Thanks for your query.
Read and understood your concerns about the hole at a place where last molar was removed last year.
The probable cause is retailed tooth part or osteomyelitis locally.
I would advise you in such a situation to consult your Dentist, go for X-ray to see what is retained and get it removed. The would will heal within 7 days.
I hope this answer helps you to take a proper decision.
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